*** - Description: Develop a simulator for an online payment gateway to understand transaction processing. - Features: - Handle various payment methods (credit cards, bank transfers, etc.). - Simulate payment authorization and capture. - Implement fraud detection algorithms. - Generate transaction reports. - Provide API for merchants to integrate. - Technologies: - Backend: Kotlin, Spring Boot - Frontend: Vaadin - Database: PostgreSQL - Messaging: Apache Kafka / RabbitMQ